Polyethylene terephthalate (PET) when used as a thermoplastic molding resin crystallizes slowly at moderate molding temperatures, e.g. below 130.degree.. Deyrup in reissued U.S. Pat. No. Re. 32,334 discloses the use of a sodium or potassium salt of a hydrocarbon acid, e.g. stearic acid, together with other low molecular weight organic compounds to provide a reinforced PET molding resin that crystallizes rapidly at low temperatures. The value of alkali metal salts of fatty acids as crystallization accelerators for PET is also disclosed by Hayashi et al. in U.S. Pat. No. 4,368,286. Such crystallized PET molding resins generally are brittle, i.e. have low impact resistance.
Castelnuovo et al. disclose in U.S. Pat. No. 3,919,353 impact resistant molding compositions comprising PET and up to about 30% of graft rubber composition, e.g. crosslinked butadiene grafted with styrene and methyl methacrylate (MBS).
Lindner et al. disclose in U.S. Pat. No. 4,417,026 thermoplastic polyester molding compositions having improved toughness comprising blends of polyester, e.g. PET, and up to 40% by weight of graft copolymer having a diene rubber core surrounded by an acrylate rubber first shell and a thermoplastic outer shell.
Farnham et al. disclose in U.S. Pat. No. 4.096,202 impact resistant polyester, e.g. PET, and acrylate core shell copolymers.
Dunkle et al. disclose in U.S. Pat. No. 4,659,767 impact modified polyester blends comprising PET, acrylate core shell polymer and acid-containing olefin copolymers, e.g. ethylene methacrylic acid copolymer, and zinc salts thereof.
Hornbaker et al. disclose in U.S. Pat. No. 4,526,923 blends of PET and styrene maleic anhydride copolymers including rubber-modified copolymers which have relatively poor notched impact resistance.
Semen et al. disclose in U.S. Pat. No. 4,483,949 that nucleating agents such as sodium stearate have an adverse effect on the toughness of blends of PET and styrene-maleic anhydride copolymers.